Polishing pad showing intrinsic abrasion and fabrication method thereof

ABSTRACT

A polishing pad showing intrinsic abrasion automatically during processing. In the pad of the present invention, a polishing substrate has a first surface, a first index a first predetermined distance from the first surface, a second index a second predetermined distance from the first surface, and a third index a third predetermined distance from the first surface, wherein the third predetermined distance exceeds the second predetermined distance, and the second predetermined distance exceeds the first predetermined distance. The polishing pad shows the first pattern when abrasion from the first surface exceeds the first predetermined distance, and shows the first and second patterns when abrasion from the first surface exceeds the second predetermined distance. The first, second and third patterns appear when abrasion from the first surface exceeds the third predetermined distance.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a polishing pad, and in particular to a polishing pad showing intrinsic abrasion automatically during processing, as well as the fabrication method thereof.

[0003] 2. Description of the Related Art

[0004] During the manufacture of integrated circuits it is necessary to polish a thin wafer of semiconductor material in order to remove material and dirt from the surface thereof. Typically, a wet chemical abrasive or slurry is applied to a motor driven polishing pad while a semiconductor wafer is pressed against it in a process well known as chemical mechanical polishing (CMP). The polishing effects on the wafer result from both the chemical and mechanical actions.

[0005] The polishing pad contacts the wafer surface while both wafer and pad are rotating on different axes. The rotation facilitates the transport of the abrasive containing polishing slurry between the pad and the wafer. The condition of the polishing pad directly affects the polishing rate of material removal and uniformity of the removal from the semiconductor wafer. Pad conditioning may take place during or after the polishing process. The most common method of pad conditioning is a mechanical abrasion of the pad surface. Materials such as steel blades or abrasive wheels are often used. While conditioning of the pad surface improves polishing uniformity and rates, it has the detrimental effect of removing a quantity of pad material. However, the polishing removal rate still diminishes as the abrasion of the polishing pad exceeds a predetermined quantity. Therefore, the polishing removal uniformity is degraded.

[0006] Presently, the only means available to measure pad material removal are destructive to the polishing pad, such as cutting a piece from the pad and using a micrometer to measure remaining thickness, or contacting the pad using a micrometer and a straightedge across the pad surface. Thus, pad destruction or pad contamination may result.

SUMMARY OF THE INVENTION

[0007] Accordingly, an object of the invention is to provide a polishing pad indicating the need for replacement of the old polishing pad at a suitable time, thereby maintaining polishing removal uniformity of a wafer.

[0008] Another object of the invention is to provide a polishing pad showing abrasion level without pad destruction or pad contamination caused by the measurement, as currently performed in the prior art.

[0009] According to the above mentioned objects, the present invention provides a method for fabricating a polishing pad showing intrinsic abrasion during processing.

[0010] In the method of the present invention, a polishing substrate with a first and second surface is provided. Next, a plurality of first apertures with a first predetermined depth, a plurality of second apertures with a second predetermined depth and a plurality of third apertures with a third predetermined depth are formed on the second surface of the polishing substrate by machining or a laser device. In this case, the first predetermined depth exceeds the second predetermined depth, and the second predetermined depth exceeds the third predetermined depth.

[0011] According to the above mentioned objects, the invention also provides a polishing pad showing intrinsic abrasion automatically during processing.

[0012] In the polishing pad of the present invention, a polishing substrate deposited on the polishing platen has a first surface, a second surface, a first index a first predetermined distance from the first surface, a second index a second predetermined distance from the first surface, and a third index a third predetermined distance from the first surface, wherein the third predetermined distance exceeds the second predetermined distance, and the second predetermined distance exceeds the first predetermined distance. The polishing pad shows the first pattern when abrasion from the first surface exceeds the first predetermined distance, and shows the first and second patterns when abrasion from the first surface exceeds the second predetermined distance, and shows the first, second and third patterns when abrasion from the first surface exceeds the third predetermined distance.

[0013] A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

[0015]FIGS. 1a and 1 b are cross-sections of the fabricating method according to the present invention;

[0016]FIGS. 2a to 5 a are cross-sections of the polishing pad according to the present invention during different abrasions; and

[0017]FIGS. 2b to 5 b are plane views of the polishing pad according to FIGS. 2a to 5 a.

DETAILED DESCRIPTION OF THE INVENTION

[0018]FIGS. 1a and 1 b are cross-sections of the fabricating method according to the present invention.

[0019] First, a polishing substrate 100 with a first surface SF1 and a second surface SF2 is provided. For example, the polishing substrate 100 can be a polyurethane substrate. Generally, a cylinder of polyurethane is formed, and is divided into several polishing pads with predetermined thickness, wherein the predetermined thickness is in the millimeter range.

[0020] Next, a plurality of first indices, a plurality of second indices and a plurality of third indices are formed in the polishing pad 100, wherein the first indices, the second indices and third indices are arranged into first, second and third patterns respectively. The first indices are all at a first predetermined distance from the first surface SF1, wherein the first predetermined distance is 0.2 mm to 0.3 mm. The second indices are all a second predetermined distance from the first surface SF1, wherein the second predetermined distance is 0.4 mm to 0.5 mm. The third indices are all a third predetermined distance from the first surface SF1, wherein the third predetermined distance is 0.6 mm to 0.7 mm. Next, the second surface of polishing pad 100 is combined with a soft pad and is disposed on a polishing platen to polish wafers with slurry.

[0021] In this case, the first, second and third indices are apertures formed by a laser device or machining. That is to say, a plurality of first apertures V1 are formed on the second surface SF2 and the first apertures V1 all have a first predetermined depth d1, for example 0.6 mm˜0.7 mm. A plurality of second apertures V2 are formed on the second surface SF2 and the second apertures V2 all have a second predetermined depth d2, for 0.5 mm˜0.4 mm. A plurality of third apertures V3 are formed on the second surface SF2 and the third apertures V3 all have a third predetermined depth d3, for 0.3 mm˜0.2 mm. In addition, the first, second and third apertures (V1, V2 and V3) arrange in first, second and third patterns, for example concentric circles with different diameters.

[0022]FIGS. 2a to 5 a are cross-sections of the polishing pad with different abrasions according to the present invention during processing, and FIGS. 2b to 5 b are plane views of the polishing pad according to FIGS. 2a to 5 a.

[0023] As shown in FIGS. 2a and 2 b, the polishing pad 100 shows nothing on its first surface SF1 when the polishing pad 100 is new or the intrinsic abrasion of pad 100 does not exceed the first predetermined distance T1. That is to say, neither the first, second or third patterns may be shown on the first surface SF1 of the polishing pad 100. The abrasion of the polishing pad 100 increases with use thereof. As the abrasion of the pad 100 from the first surface SF1 increases and exceeds the first predetermined distance T1, the polishing pad shows the first pattern, for example a circle, on its first surface as shown in FIG. 3b.

[0024] Next, the polishing pad 100 shows the first and second patterns on its first surface SF1 when abrasion from the first surface SF1 exceeds the second predetermined distance T2 as shown in FIGS. 4a and 4 b. At this time, the polishing pad 100 shows the first and second patterns (P1 and P2), for example two concentric circles with different diameters.

[0025] Next, the polishing pad 100 shows the first, second and third patterns on its first surface SF1 when abrasion from the first surface SF1 exceeds the third predetermined distance T3 as shown in FIGS. 5a and 5 b. At this time, the polishing pad 100 shows the first, second and third patterns (P1, P2 and P3), for example three concentric circles with different diameters.

[0026] In this embodiment of the present invention, the first, second and third indices are arranged in circles with different diameters by apertures formed by a laser device or machining, it is to be understood that the invention is not limited to the disclosed embodiments.

[0027] Therefore, the polishing pad of the present invention can show different patterns according to different levels of intrinsic abrasion. Thus, the invention can to show the abrasion of the polishing pad without pad destruction or pad contamination caused by measurement methods in the prior art. Accordingly, the invention can advise replacement of the old polishing pad at a suitable time, thereby maintaining polishing removal uniformity of a wafer.

[0028] While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

What is claimed is:
 1. A method of fabricating a polishing pad showing intrinsic abrasion during processing, comprising: providing a polishing substrate with a first and second surface; forming a plurality of first sign apertures with a first predetermined depth on the second surface of the polishing substrate; forming a plurality of second sign apertures with a second predetermined depth on the second surface of the polishing substrate; and forming a plurality of third sign apertures with a third predetermined depth on the second surface of the polishing substrate, wherein the first predetermined depth exceeds the second predetermined depth, and the second predetermined depth exceeds the third predetermined depth.
 2. The method as claimed in claim 1, wherein the first sign apertures, the second sign apertures and the third sign apertures on the polishing substrate are formed by a laser device.
 3. The method as claimed in claim 1, wherein the first sign apertures, the second sign apertures and the third sign apertures on the polishing substrate are formed by machining.
 4. The method as claimed in claim 1, wherein the first sign apertures, the second sign apertures and the third sign apertures on the polishing substrate are arranged in a first predetermined pattern, a second predetermined pattern and a third predetermined pattern, respectively.
 5. The method as claimed in claim 4, wherein the first predetermined pattern, the second predetermined pattern and the third predetermined pattern are concentric circles with different diameters.
 6. The method as claimed in claim 1, wherein the first predetermined depth of the first sign apertures is between 0.6 mm to 0.7 mm.
 7. The method as claimed in claim 1, wherein the second predetermined depth of the second sign apertures is between 0.4 mm to 0.5 mm.
 8. The method as claimed in claim 1, wherein the third predetermined depth of the third sign apertures is between 0.2 mm to 0.3 mm.
 9. A polishing device, comprising: a polishing platen; a polishing substrate deposited on the polishing platen, having a first surface, a second surface, a first index at a first predetermined distance from the first surface, a second index a second predetermined distance from the first surface, and a third index a third predetermined distance from the first surface, wherein the third predetermined distance exceeds the second predetermined distance, and the second predetermined distance exceeds the first predetermined distance.
 10. The polishing device as claimed in claim 9, wherein the first, second and third indices are composed of apertures, and the first predetermined distance is 0.2 mm to 0.3 mm.
 11. The polishing device as claimed in claim 9, wherein the second predetermined distance is 0.4 mm to 0.5 mm.
 12. The polishing device as claimed in claim 9, wherein the third predetermined distance is 0.6 mm to 0.7 mm.
 13. The polishing device as claimed in claim 9, wherein the first, second and third indices are concentric circles arranged by apertures.
 14. A polishing pad showing intrinsic abrasion automatically during processing, comprising: a polishing substrate having a first and second surface; a plurality of first apertures a first predetermined distance from the first surface; a plurality of second apertures a second predetermined distance from the first surface; and a plurality of third apertures a third predetermined distance from the first surface, wherein the apertures extend along a direction from the second surface to the first surface, the third predetermined distance exceeds the second predetermined distance, and the second predetermined distance exceeds the first predetermined distance.
 15. The polishing pad as claimed in claim 14, wherein the first apertures, the second apertures and the third apertures on the polishing substrate are arranged in a first predetermined pattern, a second predetermined pattern and a third predetermined pattern, respectively.
 16. The polishing pad as claimed in claim 14, wherein the polishing pad shows the first pattern when abrasion from the first surface exceeds the first predetermined distance, and shows the first and second patterns when abrasion from the first surface exceeds the second predetermined distance, and shows the first, second and third patterns when abrasion from the first surface exceeds the third predetermined distance.
 17. The polishing pad as claimed in claim 14, wherein the third predetermined distance is 0.6 mm to 0.7 mm.
 18. The polishing pad as claimed in claim 14, wherein the second predetermined distance is 0.4 mm to 0.5 mm.
 19. The polishing pad as claimed in claim 14, wherein the first predetermined distance is 0.2 mm to 0.3 mm.
 20. The polishing pad as claimed in claim 15, wherein the first predetermined pattern, the second predetermined pattern and the third predetermined pattern are concentric circles with different diameters. 